v3.26.1
DEBT SECURITIES - Available-for-Sale Investments Classified by Contractual Maturity Date (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Dec. 31, 2024
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost $ 5,022,891 $ 4,901,982    
Gross Unrealized Gains 3,866 7,196    
Gross Unrealized Losses 357,221 354,383    
Allowance for Credit Losses 839 763 $ 516 $ 521
Fair value $ 4,668,697 $ 4,554,032    
Weighted-average yield 2.48% 2.31%    
Interest receivable $ 67,722 $ 71,351    
Available-for-Sale Securities [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Interest receivable 11,400 9,400    
Federal Home Loan Bank Borrowings [Member] | Asset Pledged as Collateral [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost 247,200 251,000    
Fair value 226,400 230,200    
U.S. Treasury securities [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost Due within one year 497,272 497,159    
Gross Unrealized Gains Due within one year 2 183    
Gross Unrealized Losses Due within one year 20 0    
Allowance for Credit Losses within one year 0 0    
Fair value Due within one year $ 497,254 $ 497,342    
Weighted-average yield Due within one year 3.65% 3.85%    
U.S. GSE's obligations [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost Due within one year $ 455,779 $ 402,352    
Gross Unrealized Gains Due within one year 9 17    
Gross Unrealized Losses Due within one year 6,614 4,659    
Allowance for Credit Losses within one year 0 0    
Fair value Due within one year $ 449,174 $ 397,710    
Weighted-average yield Due within one year 0.98% 0.92%    
Amortized cost After 1 to 5 years $ 381,229 $ 500,025    
Gross Unrealized Gains After 1 to 5 years 0 5    
Gross Unrealized Losses After 1 to 5 years 11,614 16,114    
Allowance for Credit Losses After 1 to 5 years 0 0    
Fair value After 1 to 5 years $ 369,615 $ 483,916    
Weighted-average yield After 1 to 5 years 2.08% 1.45%    
Amortized cost After 5 to 10 years $ 14,995 $ 14,996    
Gross Unrealized Gains After 5 to 10 years 0 0    
Gross Unrealized Losses After 5 to 10 years 130 11    
Allowance for Credit Losses After 5 to 10 years 0 0    
Fair value After 5 to 10 years $ 14,865 $ 14,985    
Weighted-average yield After 5 to 10 years 4.75% 4.75%    
Amortized cost After 10 years $ 6,298 $ 6,547    
Gross Unrealized Gains After 10 years 0 0    
Gross Unrealized Losses After 10 years 35 46    
Allowance for Credit Losses After 10 years 0 0    
Fair value After 10 years $ 6,263 $ 6,501    
Weighted-average yield After 10 years 3.95% 3.97%    
Puerto Rico government obligations [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost After 10 years $ 2,655 $ 2,700    
Gross Unrealized Gains After 10 years 0 0    
Gross Unrealized Losses After 10 years 738 762    
Allowance for Credit Losses After 10 years 308 318    
Fair value After 10 years $ 1,609 $ 1,620    
Weighted-average yield After 10 years 0.00% 0.00%    
Allowance for Credit Losses $ 308 $ 318 340 345
United States And Puerto Rico Government Obligations [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost 1,358,228 1,423,779    
Gross Unrealized Gains 11 205    
Gross Unrealized Losses 19,151 21,592    
Allowance for Credit Losses 308 318    
Fair value $ 1,338,780 $ 1,402,074    
Weighted-average yield 2.32% 2.18%    
Residential MBS [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost $ 3,431,214 $ 3,240,106    
Gross Unrealized Gains 3,556 6,483    
Gross Unrealized Losses 302,533 297,249    
Allowance for Credit Losses 531 445    
Fair value $ 3,131,706 $ 2,948,895    
Weighted-average yield 2.55% 2.36%    
Weighted average remaining contractual life 16 years 10 months 24 days 16 years 3 months 18 days    
Residential MBS [Member] | U.S. Agencies MBS [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost $ 2,408,684 $ 2,401,704    
Gross Unrealized Gains 1,360 2,360    
Gross Unrealized Losses 259,497 256,589    
Allowance for Credit Losses 0 0    
Fair value $ 2,150,547 $ 2,147,475    
Weighted-average yield 1.89% 1.80%    
Residential MBS [Member] | Collateralized mortgage obligations ("CMOs") issued or guaranteed by FHLMC, FNMA and GNMA [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost $ 1,017,683 $ 833,330    
Gross Unrealized Gains 2,196 4,123    
Gross Unrealized Losses 41,833 39,299    
Allowance for Credit Losses 0 0    
Fair value $ 978,046 $ 798,154    
Weighted-average yield 4.10% 3.95%    
Residential MBS [Member] | Private label [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost $ 4,847 $ 5,072    
Gross Unrealized Gains 0 0    
Gross Unrealized Losses 1,203 1,361    
Allowance for Credit Losses 531 445 $ 176 $ 176
Fair value $ 3,113 $ 3,266    
Weighted-average yield 5.95% 5.92%    
Commercial Mortgage Backed Securities [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost $ 233,449 $ 238,097    
Gross Unrealized Gains 299 508    
Gross Unrealized Losses 35,537 35,542    
Allowance for Credit Losses 0 0    
Fair value $ 198,211 $ 203,063    
Weighted-average yield 2.42% 2.42%    
Weighted average remaining contractual life 28 years 9 months 18 days 29 years 1 month 6 days    
Mortgage Backed Securities [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost $ 3,664,663 $ 3,478,203    
Gross Unrealized Gains 3,855 6,991    
Gross Unrealized Losses 338,070 332,791    
Allowance for Credit Losses 531 445    
Fair value $ 3,329,917 $ 3,151,958    
Weighted-average yield 2.54% 2.36%    
Uninsured Portion Of Government Deposits [Member] | Asset Pledged as Collateral [Member]        
Schedule Of Available For Sale Securities [Line Items]        
Amortized cost $ 2,600 $ 2,700,000    
Fair value $ 2,400 $ 2,500,000